Scroll compressor having an electric motor incorporated

ABSTRACT

In a scroll compressor with an electric motor incorporated of the present invention, a housing is provided with a cooling chamber which is provided adjacently on the outer peripheral side of a motor portion, so that cooling fluid is supplied to the cooling chamber, and a high pressure chamber which is provided adjacently on the outer peripheral side of the cooling chamber so that a gas, compressed by a fixed scroll and a movable scroll, is supplied to the high pressure chamber. Consequently, reduction in the mass flow rate of the discharge gas of the compressor can be suppressed, and it is possible to cool both the discharge gas and the motor portion by the single cooling chamber.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a scroll compressor and, morespecifically, it relates to a scroll compressor having an electric motorincorporated for compressing a gas to be supplied to a fuel cell.

[0003] 2. Description of the Related Art

[0004] In recent years, the automobile industry has increasingly beenplacing emphasis on electric motor cars in the hope of reducing theconsumption of petroleum resources. A fuel cell, as a drive source foran electric motor car, exhibits high energy conversion efficiency and isenvironmentally friendly because only nontoxic reaction products, suchas water or carbon dioxide, are produced and, hence, it is expected thatthe demand for fuel cell system will increase. A scroll compressor whichcan be made small and light is suitable as a compressor to compressgases to be supplied to the fuel cell.

[0005] It is preferable that the rise in temperature of the air isrestricted so that the work load of the scroll compressor is small. Tothis end, as in a scroll compressor disclosed in Japanese UnexaminedPatent Publication (Kokai) No. 8-247056, a cooling chamber is providedaround a high-pressure chamber to circulate cooling water, to therebyrestrict a rise in temperature of the highly pressurized air.

[0006]FIG. 2 shows an axial sectional view of a known scroll compressor.In the known scroll compressor, a housing 1 is comprised of a frontcasing 2, a rear casing 3 and an end plate 20. The front casing 2 has asmall diameter portion at a front side thereof, having a recess at afront end surface of the small diameter portion, and a large diameterportion at a rear side thereof. The end plate 20 is provided at thefront side of the front casing 2, and the rear casing 3 is provided atthe rear side of the front casing 2.

[0007] A fixed scroll 21 which extends in the axial direction isprovided at a boundary surface 2 a in the front casing 2. A suctionportion 22 is formed on the outer peripheral portion of the fixed scroll21, and a discharge portion 25 is formed on the inner peripheral portionof the fixed scroll 21. A discharge valve 24 and a high pressure chamber25 are formed in front of the discharge portion 23. A crank-shaped driveshaft 30 is rotatably supported at its one end (rear end) of the rearcasing 3. An end plate 32, which is provided with an axially extendingmovable scroll 31, is rotatably connected to the other end of the driveshaft 30.

[0008] When the drive shaft 30 rotates to make orbital movement of themovable scroll 31, the space defined between the fixed scroll 21 and themovable scroll 31 is reduced in volume and hence the air in the space isgradually compressed and is moved toward the discharge portion 23. Theair reaching the discharge portion 23 is discharged to the outside ofthe compressor from a discharge port 20 a through the discharge valve 24and the high pressure chamber 25.

[0009] The cooling water is introduced into a cooling chamber 26 throughan inlet port not shown. The cooling chamber 26 is located adjacent thehigh pressure chamber 25. Consequently, the temperature of the coolingwater is increased due to heat transferred from the highly pressurizedair in the high pressure chamber 25. The cooling water whose temperaturehas been increased is discharged to the outside of the compressor froman outlet port not shown. In a known scroll compressor, the dischargedgas, i.e., the highly pressurized air is cooled in the way mentionedabove.

[0010] It is necessary to provide an electric motor or the like as adrive means in the scroll compressor. In a scroll compressor with amotor integrally incorporated therein, the compressor system includingthe motor can be entirely made small. Therefore, the scroll compressorwith an electric motor incorporated is particularly advantageously usedas a compressor for supplying a gas to a fuel cell which is in aremarkably restricted accommodation space. In a scroll compressor withan electric motor incorporated, it is necessary to remove heat generatedfrom a rotor or the like which rotates at high speed, in the motor. Tothis end, a cooler such as a fan is provided in the motor, in additionto the cooling chamber for cooling the highly pressurized air.

[0011] The gas to be supplied to the fuel cell, i.e., the discharge gasof the compressor must be humidified to some extent. To this end, avapor exchange diaphragm is provided in the vicinity of the dischargeport of the compressor to humidify the discharged gas. Theheat-resistance critical temperature of the vapor exchange diaphragm isapproximately 140° C. Therefore, the temperature of the discharge gasmust be cooled to below the critical temperature. From only theviewpoint of cooling of the discharge gas, a conventional compressorhaving a cooling chamber could be used for the fuel cell.

[0012] However, if the conventional scroll compressor with an electricmotor incorporated is used for the fuel cell, the following problems areraised. For the gas to be supplied to the fuel cell, i.e., the dischargegas of the compressor, it is preferable that the mass flow rate isincreased because the mass of the gas to be supplied to the fuel cell isincreased. However, the cooling chamber of the conventional scrollcompressor is formed in front of the end face of the front casing and,hence, the gas introduced into the compressor from the outer peripheralside of the end face can be heated by the cooling water which has beensubjected to heat exchange.

[0013] If the suction gas is heated and consequently its volume isincreased, the density is reduced but the volume flow rate is constant.Consequently, the mass flow rate of the suction gas is reduced and,accordingly, the mass flow rate of the discharge gas is reduced. Namely,in the conventional compressor in which the cooling chamber is formed atthe end face, the mass of the gas to be supplied to the fuel cell isreduced.

[0014] Moreover, as mentioned above, in the conventional scrollcompressor with an electric motor incorporated, the cooling means forthe motor portion and the cooling means (cooling chamber) for the highlypressurized air are separately provided.

[0015] The inventor of the present invention has discovered that if ahigh pressure chamber to which the discharge gas after compression issupplied, is provided on the motor side of the housing, and only onecooling chamber as a cooling means is provided adjacent both the highpressure chamber and a motor portion, not only can reduction in the massflow rate of the discharge gas be suppressed but also the discharge gasand the motor portion can be cooled by the single cooling means.

SUMMARY OF THE INVENTION

[0016] A scroll compressor with an electric motor incorporated of thepresent invention has been completed, based on the above-mentioneddiscovery. It is an object of the present invention to prevent the massflow rate of the discharge gas from being reduced and to make itpossible to cool both the discharge gas and the motor portion by asingle cooling chamber.

[0017] A scroll compressor with an electric motor incorporated,according to the present invention, comprises a housing accommodating acompressor portion and a motor portion, the motor portion driving amovable scroll, and the compressor portion having a fixed scroll securedto the housing and the movable scroll which is located eccentricallywith respect to the fixed scroll so as to orbit with respect to thefixed scroll, a cooling chamber which is provided adjacently on theouter peripheral side of the motor portion, and a high pressure chamberwhich is provided adjacently on the outer peripheral side of the coolingchamber, so that gas compressed by the fixed scroll and the movablescroll is supplied to the high pressure chamber, wherein a cooling fluidis supplied to the cooling chamber to cool both the gas and the motorportion.

[0018] Namely, the scroll compressor with an electric motor incorporatedaccording to the present invention is characterized in that a highpressure chamber, to which the compressed gas is supplied, is providedon the outer peripheral side of the motor portion and a cooling chamber,to which the cooling fluid is supplied, is provided on the innerperipheral side of the high pressure chamber. In other words, the motorportion, the annular cooling chamber and the annular high pressurechamber are arranged in this order in the radial direction, from theinner peripheral side.

[0019] Since the high pressure chamber and the cooling chamber areprovided on the outer peripheral side of the motor portion and thesuction port of the gas is provided on the compressor portion side,there is no fear that the suction gas introduced in the compressorportion is heated by the cooling fluid whose temperature has risen inthe cooling chamber. Consequently, it is possible to prevent the massflow rate of the gas to be supplied to the fuel cell from being reduced.Moreover, it is possible to effectively cool both the gas and the motorportion by means of the single cooling chamber.

[0020] The present invention may be more fully understood from thedescription of preferred embodiments of the invention, as set forthbelow, together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In the drawings;

[0022]FIG. 1 is an axial sectional view of a scroll compressor with anelectric motor incorporated, according to the present invention; and

[0023]FIG. 2 is an axial sectional view of a known scroll compressor.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] An embodiment of the invention will be discussed below withreference to the accompanying drawing. In FIG. 1 shows an axialsectional view of a scroll compressor with an electric motorincorporated, according to an embodiment of the invention. A compressionportion is provided in a housing 1. The housing 1 is constituted by acup-shaped front casing 2 of an aluminum alloy, a cylindrical rearcasing 3 of an aluminum alloy, a cup-shaped motor casing 4 of analuminum alloy and a bottom plate 41 of an aluminum alloy. The frontcasing 2 is provided at its bottom center portion with a discharge port20 a. The rear casing 3 is located at an open end of the front casing 2and is provided with a small diameter portion, a large diameter portionwith an end recess 3 a, and a disc-shaped separation portion 3 b betweenthe small diameter portion and the large diameter portion. The motorcasing 4 is provided on its outer peripheral surface with an annularrecess 4 a and an annular projection 4 b adjacent thereto and isprovided on its bottom center portion with a hole. An open end of themotor casing 4 is fitted in the inner peripheral surface of the largediameter portion of the rear casing 3. The bottom plate 41 is attachedto the motor casing 4 to cover the bottom hole thereof.

[0025] A high pressure chamber 25 is defined by closing the recess 3 a,which is formed in the large diameter portion of the rear casing 3 withthe projection 4 b on the outer peripheral surface of the motor casing4, in assembling the motor casing 4 to fit in the inner peripheralsurface of the large diameter portion of the rear casing 3.

[0026] A gas passage 6 for highly pressurized gas extends between thehigh pressure chamber 25 and the discharge port 20 a of the front casing2. The gas passage 6 is provided with a steel cylindrical elbow 60connected to the discharge port 20 a, a steel pipe 61 connected to theelbow 60, a steel elbow 62 connected to the steel pipe 61, a steel pipe63 connected to the elbow 62, and a steel elbow 64 connected to thesteel pipe 63. The steel pipe 63 is fitted at the other end in the largediameter portion of the rear casing 3 and opens into the high pressurechamber 25. A discharge pipe 80 is inserted in the large diameterportion of the rear casing 3 and opens to the high pressure chamber 25.

[0027] In assembling the motor casing 4 to fit in the inner peripheralsurface of the large diameter portion of the rear casing 3, the innerperipheral surface of the large diameter portion of the rear casing 3covers the recess 4 a of the motor casing 4 in the axial direction todefine an annular cooling chamber 26. A steel inlet pipe 70 and a steeloutlet pipe 71 extend through the projection 4 b of the motor casing 4and open to the cooling chamber 26.

[0028] A motor portion 5 is provided in the motor casing 4 and isconstituted by an annular stator 50 on the inner peripheral surface ofthe motor casing 4, a coil 51 wound in a slit (not shown) of the stator50, an annular rotor 52 made of a magnetic material and arranged at theinner side of the stator 50, a part of the drive shaft extending in theaxial direction at the center portion of the rotor 52, and a ballbearing which rotatably supports the drive shaft 30 at the bottomportion of the motor casing 4.

[0029] The basic structure of the compressor portion of the scrollcompressor with an electric motor incorporated in the illustratedembodiment is substantially described in FIG. 2.

[0030] In FIG. 3 of the embodiment of the invention, no end plate 20 isprovided; the cooling chamber 26 and the high pressure chamber 25 areprovided on the outer peripheral side of the motor portion 5; the driveshaft 30 extends to the motor portion 5; and the rear casing 3 isdifferent in shape from the rear casing in FIG. 2.

[0031] The flow of air, as the gas for the scroll compressor with anelectric motor incorporated in the illustrated embodiment, will bediscussed below.

[0032] When the drive shaft is rotated by driving the electric motor anda movable scroll 31 orbits. Air closed in a suction portion 22 at theouter peripheral side of the movable scroll 31 is gradually transferredto the center side of the movable scroll 31 and is compressed due to theorbit of the movable scroll 31 by decreasing the volume of the spaceclosing the air.

[0033] The air compressed by the fixed scroll 21 and the movable scroll31 is discharged into the high pressure gas passage 6 from the dischargeportion 23 through the discharge valve 24. The air passing in the gaspassage 6 is introduced in the annular high pressure chamber 25. The aircirculates in the high pressure chamber 25 and is discharged to theoutside of the compressor through the discharge pipe 80.

[0034] The flow of water, as the cooling fluid for the scroll compressorwith an electric motor incorporated in the illustrated embodiment, willbe discussed below.

[0035] The water introduced in the annular cooling chamber 26 throughthe inlet pipe 70 circulates therein. During the circulation of thewater, the heat is transferred to the water from the compressed air inthe high pressure chamber 25 provided on the outer peripheral side ofthe cooling chamber 26, and from the motor portion 5 provided on theinner peripheral side of the cooling chamber 26. Consequently, thewater, whose temperature has risen, is discharged to the outside of thecompressor from the outlet pipe 71. There are externally provided aradiator which cools the heated water and a pump which feeds thepressurized water, so that the water cooled by the radiator isintroduced again into the compressor through the inlet pipe 70, althoughthe details thereof are not shown in the drawings.

[0036] In the illustrated embodiment, the housing is constituted by thefront casing 2, the rear casing 3, the motor casing 4, and the bottomplate 41. In place of the housing which is made of an assembly of aplurality of elements, it is alternatively possible to form some of theelements integrally. Moreover, although the fixed scroll 21 is formed ata boundary surface 2 a of the front casing 2 and is secured to thehousing, it is alternatively possible to arrange a separate memberhaving a fixed scroll in the housing. This alternative is included inthe concept of securing the fixed scroll to the housing.

[0037] Although air is used as the gas to be compressed by thecompressor portion in the illustrated embodiment, the kind of the gas isnot limited to a specific one. If further enhanced hermetic sealing ofthe compressor portion is established, hydrogen gas or the like, whichis fuel used for the fuel cell, can be used.

[0038] The size and shape of the cooling chamber are not limited tospecific ones. For instance, in an arrangement in which the radiatorfins are provided in the cooling chamber, the heat transfer area isincreased and, hence, the cooling efficiency is enhanced. Furthermore,it is possible to provide a corrugated separation wall between thecooling chamber and the high pressure chamber and/or between the coolingchamber and the motor portion in order to further increase the heattransfer area.

[0039] In the illustrated embodiment, the cooling chamber 26 is formedby fitting the motor casing 4 in the rear casing 3. With thisarrangement, the cooling chamber can be easily formed. However, it isalternatively possible to use a separate member which defines therein acooling chamber and which is attached to the motor casing. In thisalternative, the cooling chamber is highly liquid-tight due to theseamless wall thereof. The separate member which defines therein acooling chamber forms a part of the housing.

[0040] The material of which the cooling chamber is formed is notlimited to a specific material. In the illustrated embodiment, thecooling chamber is formed by a member made of an aluminum alloy. Thealuminum alloy exhibits a high heat transfer rate, thus leading to anenhanced cooling efficiency. The cooling chamber can be formed of a diecasting.

[0041] Although water is used as the cooling fluid, the kind of thecooling fluid is not limited to specific fluid. Any medium which isliquid at the temperature of the environment in which the compressor isused, and which does not corrode the material of the equipment, can beappropriately selected. It is possible to use pure water, which isproduced by the fuel cell, as the cooling fluid.

[0042] Although the special-purpose cooling circuit for the compressoris used in the illustrated embodiment, it is possible to add a coolingchamber to a cooling circuit provided in an automobile or the like tocool other devices therein. Absence of an additional cooling circuitcontributes to reduction in the accommodation space and manufacturingcost. Alternatively, it is also possible to discharge the used coolingfluid without recirculating the cooling fluid. Absence of arecirculating circuit of the cooling fluid simplifies the compressor andreduces the accommodation space.

[0043] Although the gas passage for highly pressurized gas is made of aplurality of steel pipes and elbows in the illustrated embodiment, it ispossible to form the gas passage of a single piece of pipe. The singlepiece of pipe contributes to an enhancement of the sealing efficiency.Although the gas passage for highly pressurized gas is provided outsideof the housing in the illustrated embodiment, it is possible to providethe gas passage in the housing. If the gas passage is provided in thehousing, no interference with other devices, provided in an automobileor the like, occurs so that the reliability can be enhanced and theaccommodation space can be reduced.

[0044] The kind and internal structure of the motor are not limited tospecific ones. Although an inverter-controlled motor is used in theillustrated embodiment, it is possible to use a DC motor.

[0045] The shape of the rotor and the stator of the motor portion andthe arrangement of the coil and the magnetic material therein are notspecifically limited. Although the coil is located on the stator sideand the magnetic material is located on the rotor side, in theillustrated embodiment, it is possible to use a motor in which themagnetic material is located on the stator side and the coil is locatedon the rotor side.

[0046] Although the rotary shaft of the motor is used as the drive shaftof the movable scroll of the compressor portion in the illustratedembodiment, it is alternatively possible to provide a drive shaft of themovable scroll separate from the rotary shaft of the motor. In thisalternative, the drive shaft of the movable scroll and the rotary shaftof the motor are connected by means of a rotation transmissionmechanism. The drive shaft in the present invention is constituted bythe rotary shaft of the motor, the rotation transmission mechanism andthe drive shaft of the movable scroll. In order to change the number ofrevolutions of the rotary shaft of the motor and the drive shaft of themovable scroll, it is possible to provide a rotation change device inthe rotation transmission mechanism.

[0047] In a scroll compressor with an electric motor incorporated,according to the present invention, the high pressure chamber and thecooling chamber are provided on the outer peripheral side of the motorportion of the housing, that is, the cooling chamber is provided betweenthe high pressure chamber and the motor portion. Consequently, reductionin the mass flow rate of the discharge gas of the compressor can besuppressed. Furthermore, it is possible to cool both the discharge gasand the motor portion by a single cooling chamber.

[0048] While the invention has been described by reference to specificembodiments chosen for purpose of illustration, it should be apparentthat numerous modification could be made thereto by those skilled in theart without departing from the basic concept and scope of the invention.

What is claimed is:
 1. A scroll compressor, with an electric motorincorporated, comprising: a housing accommodating a compressor portionand a motor portion, the motor portion driving a movable scroll, and thecompressor portion having a fixed scroll secured to the housing and themovable scroll which is located eccentrically with respect to the fixedscroll so as to orbit with respect to the fixed scroll, a coolingchamber which is provided adjacently on the outer peripheral side of themotor portion, and a high pressure chamber which is provided adjacentlyon the outer peripheral side of the cooling chamber, so that gascompressed by the fixed scroll and the movable scroll is supplied to thehigh pressure chamber, wherein a cooling fluid is supplied to thecooling chamber to cool both the gas and the motor portion.
 2. A scrollcompressor according to claim 1, wherein said high pressure chamber anda discharge port of said housing is connected by a gas passage forhighly pressurized gas formed at the outside of said housing.
 3. Ascroll compressor according to claim 1, wherein said cooling chamber andsaid high pressure chamber are formed annularly around said motorportion.
 4. A scroll compressor according to claim 1, wherein saidcooling fluid is water.